Rewrite entry parsing algorithm

Rewrite without regex crate.

The regex approach was broken. If the following _content_ was provided
in the entry:

    foo

    ---

    bar

The regex approach parsed the header until the "---" in the content.
This is, of course, not the way to do that.

Now, the parsing is implemented by hand. Should be faster as well,
though I don't care about this.

This fixes a severe bug.

doc/src/09020-changelog.md

@@ -58,6 +58,8 @@ This section contains the changelog from the last release to the next release.
       default.
     * `libimagerror` printed errors with `write!()` rather than `writeln!()`
       when tracing.
+    * A parsing error in `libimagstore`, which caused the parsing of entries
+      with a line "---" in the content part to fail, was fixed.
 
 
 ## 0.6.1

lib/core/libimagstore/Cargo.toml

@@ -21,7 +21,6 @@ maintenance                       = { status     = "actively-developed" }
 
 [dependencies]
 glob = "0.2.11"
-lazy_static = "0.2"
 log = "0.4.0"
 regex = "0.2"
 semver = "0.8"

lib/core/libimagstore/src/error.rs

@@ -28,6 +28,7 @@ error_chain! {
 
     foreign_links {
         Io(::std::io::Error);
+        Fmt(::std::fmt::Error);
         TomlDeserError(::toml::de::Error);
         GlobPatternError(::glob::PatternError);
         TomlQueryError(::toml_query::error::Error);

lib/core/libimagstore/src/lib.rs

@@ -37,7 +37,6 @@
 
 #[macro_use] extern crate log;
 extern crate glob;
-#[macro_use] extern crate lazy_static;
 extern crate regex;
 extern crate toml;
 #[cfg(test)] extern crate tempdir;

lib/core/libimagstore/src/util.rs

@@ -17,13 +17,12 @@
 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 //
 
-use regex::Regex;
+use std::fmt::Write;
+
 use toml::Value;
 
 use store::Result;
 use store::Header;
-use error::StoreErrorKind as SEK;
-use error::StoreError as SE;
 
 #[cfg(feature = "early-panic")]
 #[macro_export]
@@ -43,27 +42,23 @@ macro_rules! if_cfg_panic {
 
 pub fn entry_buffer_to_header_content(buf: &str) -> Result<(Value, String)> {
     debug!("Building entry from string");
-    lazy_static! {
-        static ref RE: Regex = Regex::new(r"(?smx)
-            ^---$
-            (?P<header>.*) # Header
-            ^---$\n
-            (?P<content>.*) # Content
-        ").unwrap();
+    let mut header          = String::new();
+    let mut content         = String::new();
+    let mut header_consumed = false;
+
+    for line in buf.lines().skip(1) { // the first line is "---"
+        if line == "---" {
+            header_consumed = true;
+            // do not further process the line
+        } else {
+            if !header_consumed {
+                let _ = writeln!(header, "{}", line)?;
+            } else {
+                let _ = write!(content, "{}", line)?;
+            }
+        }
     }
 
-    let matches = match RE.captures(buf) {
-        None    => return Err(SE::from_kind(SEK::MalformedEntry)),
-        Some(s) => s,
-    };
-
-    let header = match matches.name("header") {
-        None    => return Err(SE::from_kind(SEK::MalformedEntry)),
-        Some(s) => s
-    };
-
-    let content = matches.name("content").map(|r| r.as_str()).unwrap_or("");
-
-    Ok((Value::parse(header.as_str())?, String::from(content)))
+    Ok((Value::parse(&header)?, String::from(content)))
 }